linux-kernel - [PATCH 1/3] lib/string: allow searching for NUL with strnchr

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Date:   Mon, 6 May 2019 12:42:23 +0000
From:   Peter Rosin <peda@...ntia.se>
To:     "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>
CC:     Peter Rosin <peda@...ntia.se>,
        Matthew Wilcox <mawilcox@...rosoft.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>
Subject: [PATCH 1/3] lib/string: allow searching for NUL with strnchr

strchr considers the terminating NUL to be part of the string, and NUL
can thus be searched for with that function. For consistency, do the
same with strnchr.

Signed-off-by: Peter Rosin <peda@...ntia.se>
---
 lib/string.c | 11 ++++++++++-
 1 file changed, 10 insertions(+), 1 deletion(-)

diff --git a/lib/string.c b/lib/string.c
index 3ab861c1a857..9d64d7ab401a 100644
--- a/lib/string.c
+++ b/lib/string.c
@@ -367,6 +367,9 @@ EXPORT_SYMBOL(strncmp);
  * strchr - Find the first occurrence of a character in a string
  * @s: The string to be searched
  * @c: The character to search for
+ *
+ * Note that the %NUL-terminator is considered part of the string, and can
+ * be searched for.
  */
 char *strchr(const char *s, int c)
 {
@@ -420,12 +423,18 @@ EXPORT_SYMBOL(strrchr);
  * @s: The string to be searched
  * @count: The number of characters to be searched
  * @c: The character to search for
+ *
+ * Note that the %NUL-terminator is considered part of the string, and can
+ * be searched for.
  */
 char *strnchr(const char *s, size_t count, int c)
 {
-	for (; count-- && *s != '\0'; ++s)
+	while (count--) {
 		if (*s == (char)c)
 			return (char *)s;
+		if (*s++ == '\0')
+			break;
+	}
 	return NULL;
 }
 EXPORT_SYMBOL(strnchr);
-- 
2.11.0